Question

When the decibel level of traffic in the street goes from 40 to 60
dB, how much louder does the traffic noise seem? How much greater
is the intensity?

I am really, really stuck of the part about "how much louder does
the traffic noise seem". I need help on both parts, but especially
that one. If someone could answer that for me, it would help me out
a great deal because I am entirely lost.